TBS Discovery setup

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A guide and a few notes on how I set up my TBS Discovery. Obviously, your setup will most likely differ from the following example, but this is is still useful as a basis to continue tweaking your own setup.

Speed Controllers

  • 4x DJI OPTO 30A ESC with on-board 3.5 mm bullet sockets

Using the stock DJI speed controllers is fairly straight forward, just connect the motor, power leads and control signal wire. But if you want to use another type make sure to that the following is true:

  • Fast PWM control signal update frequency, 400 Hz - fast motor response (check SimonK, WiiESC, RapidESC)
  • Calibrate the throttle range on each ESC - for symmetric behavior of all ESC
  • Only one 5V BEC should be connected to power the flight controller - disconnect the others to avoid voltage oscillations
  • Strap the wires not the ESC board - less strain on the heatsink and transistors

Flight controller

  • DJI NAZA-M flight controller
  • DJI PMU BEC power module
  • Micro-USB cable
  • 4x 3M Gummed paper
  • 8x 3-pin Servo cables

The follwing setup and configuration will show how to install the DJI NAZA kit on a quadrotor platform.

Motor configuration

Quadcopter motor config.png

Two of the four motors rotate in the oposite direction to provide the necessary counter-torque force.

The image to the right shows how the speed controllers should be plugged into the DJI NAZA controller. Be sure to double check this before the first maiden flight, else the quad will violently turn over.

Motor configuration:

  • M1: Anti-clockwise rotation
  • M2: Clockwise rotation
  • M3: Anti-clockwise rotation
  • M4: Clockwise rotation

Gains

Attitude here refers to the auto leveling feature of the NAZA controller when the input sticks are let go off, while manual refers to the rate mode where you have to continuously adjust the control input to change the flight angle.

Setup 2012-08-19

  • DJI 2212 920KV 144W brushless motors
  • Graupner E-Prop 10x5 inch propeller set
Pid overshoot.gif

The NAZA flight controller gains in the Autopilot section will dominate how well and stable the quadcopter will behave in the air.

Manual rate:

  • Roll 145%
  • Pitch 150%
  • Yaw 125%
  • Vertical 150%

Attitude:

  • Roll 125%
  • Pitch 125%

Follow the steps below to tune and get a smooth but responsive vehicle.

  1. Reset any aileron, elevator or rudder expo and dual rates programming, same for throttle curve
  2. In NAZA Assistant set the default values of 130% for all the basic rate gains and 100% for attitude gains
  3. Start by focusing on roll (aileron) and pitch (elevator), start by increasing one value at a time by 20% and perform a test flight
  4. Pluck the aileron stick back and forth to give full input and release it to center immediately to simulate a sudden squarish change of input, the important part here is to watch for overshoot or wobbly overcorrection, if not seen increase by another 20%
  5. Once the twitchy overshoot reaction appears it means that the correction is too reactive, start to lower in 10% steps until the correction behavior is smooth again and settles fast, but still responsive, look at the figure to the right for an idea - my roll ended at 145%
  6. Do the same for roll by pulling full forward and backward stick and watch for wavy corrections on the tail end of the quadcopter - my pitch ended at 150%
  7. Yaw (rudder) gain is easier, increase by 10% and turn fast, if the flight controller overcorrects in a violent fashion, decrease by 5% - my yaw ended at 125%
  8. The last in basic gains, vertical controls the height when the throttle stick is in altitude holde position a.k.a. middle center stick - my vertical ended at 150%
  9. Lastly, the attitude gains reigns the transition between stable to desired angle (degrees/s), increasing them will move the quadcopter into position faster - my attitude gains ended at 125% for both

A note about the airframe, since it is asymmetrical and the weight is distributed rectangularly from back to front along the center line, the pitch will always be higher than the roll gain (more mass to move results in delayed reaction thus requiring steeper correction ranp).

Transmitter

Setup 2012-08-19

Dx7 control layout.png
  • Spektrum DX7 with FrSky DHT 2.4GHz 2-way 60mW transmitter / ImmersionRC EzUHF 433 MHz 200mW/600mW transmitter

This transmitter has 7 channels is programmable for both airplanes and helicopters. It has a 3-way flap switch, aileron and elevator dual rate switches, rudder mix switch, gear and aux2 switch. A preset memory makes it possible to set up several different models on the same radio.

System settings (holding down+select when powering on):

  • Model type:
    • Heli
  • Input select:
    • Aux2: F.mode - to enable three stage flight mode
    • Gear: Inh

Settings (other than defaults):

  • Reversing sw:
    • Channel 5 and 7 reverse for flight mode, others normal
  • Sub trim:
    • Gear -7 - for positioning the Attitude flight mode in DJI Assistant setup
  • Travel Adjust - adjusted for maximum resolution
    • THRO H 140% L 140%
    • AILE L 140% R 140%
    • ELEV D 140% U 140%
    • RUDD L 140% R 140%
    • GEAR + 84% - 84% - position the end-points to fit Attitude GPS and Manual flight modes
    • PIT H 100% L 100%
    • AUX2 + 100% - 100%
  • Throttle curve - to make it easy to maintain height, flat in the middle
    • ST-1 - Attitude mode
    • Point 1: 35%
    • Point 3: 65%
  • Prog. Mix1 - to provide three position flight mode
    • AUX2 -> Gear ON
    • Rate: +100%
    • SW: ON
    • Offset: 0
  • D/R & Expo
    • POS-0: - attitude mode
      • ELEV EXP +50% D/R 100%
      • AILE EXP +50% D/R 100%
      • RUDD EXP +20% D/R 100%
    • POS-1:- manual rate mode
      • ELEV EXP 60% D/R 80%
      • AILE EXP 60% D/R 80%
      • RUDD EXP 30% D/R 80%

Enable flight mode switch

When using Spektrum DX7 only the Gear-channel is available on the receiver end. To be able to use the three-position switch, it is necessary to set the Aux2-channel to F.mode (Flight mode) and map the Aux2-channel to Gear [1].

  1. Enter system mode, hold down left hand buttons while powering on and scroll to Input Select
  2. Set Aux2 to F. Mode and Gear to INH, exit the system mode
  3. Go the function list and select Prog.Mix1
  4. Set to Aux2 > Gear
  5. With f.mode switch in pos 1, set Rate +100%
  6. With f.mode switch in pos 3, set the second rate value to +100%
  7. The last 2 parameters should be set to defaults of SW:ON and OFFSET:0
  8. Now go to the Monitor Screen and check that the gear channel slider follows the Aux2 channel by moving the f.mode switch through it's range
  9. Reset the travel range for the Gear channel or Aux2 channel if necessary to get the full range

Transmitter module

Setup 2012-06-01

  • FrSky DHT 2.4GHz 60mW two-way transceiver
  • Dipole rubber duck 2dBi antenna
  • Patch antenna 14 dBi antenna

The two-way communication allows Tx and Rx signal strength to be processed in the Tx module. The module sets off an alarm when the RSSI value drops below a certain value.

Setup 2012-08-01

  • ImmersionRC EzUHF 433 MHz 200mW/600mW transmitter
  • Stock dipole 3dBi antenna

Once installed to the trainer port on the Spektrum DX7 radio, the PPM signal could be decoded by the EzUHF transmitter module. A switch makes it possible to switch between 200mW and 600mW output signal power (for emergencies).

FPV camera settings

Setup 2012-08-19

  • Security Camera 2000 PZ0420 600TVL camera

The SC2000 PZ0420 600TVL camera provides an excellent picture for a reasonable price. The only thing needed to make it perform its best is to tune a few settings to make it shine in changing light conditions [2]. Mainly the brightness, contrast, sharpness and color levels.

Do a rest to defaults before setting the following options:

  • Exposure:
    • Shutter speed: Auto
    • Brightness: 065
    • DWDR: On
      • Level: 063
  • White balance: ATW1
  • Day and night: Color
  • Image adjust:
    • Lens Shade: On
      • Level: 90
    • Contrast: 090
    • Sharpness: 031
    • Display: LCD
      • Gamma: 0.55
      • Ped level: 023
      • Color gain: 245


TBS Core setup

  • TBS Core video- and power-controller
  • Pin headers 2.0 mm pitch

Solder the Core onto the Discover frame, use the provided headers. Cut the headers to size and remove the unused pins. First solder the headers to the frame, use tape to hold the header in place, then install the Core on top of the headers. Make sure it does not touch the frame, only the headers. A helpful TBS Core install video is available from the TBS crew.

The Core provides a simple on-screen display which shows the instantaneous, total current consumption and flight time. In addition to that there is a RSSI signal strength indicator for the RC receiver control signal. Both need to be set up before they will function.

The following is a short summary of what's instructed in the TBS Core manual.

  1. Connect a video display to the video output and enable the RC control system
  2. Press the small button on the side of the TBS Core
  3. 'RSSI' should begin to blink on the display, hold the button for long periode to enter the RSSI menu
  4. A short press will change options, while a long press will confirm the action
  5. Select DIG to configure a PWM RSSI signal (EzUHF), another press will enter the max value range menu
  6. While keeping the transmitter close to the receiver, hold the button to configure the max value
  7. Then turn off the transmitter and set the min value by holding the button
  8. Now enable 100A current sensor by skipping through the menu until 'CURR' is displayed
  9. Hold the button to enter CURR and skip through to 100A, hold the button to confirm the action
  10. The OSD is now ready to be used!
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